<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
        <style>
           /* .box {
              width: 200px;
              height: 200px;
             border: 1px solid #000;
             padding: 50px;
             box-sizing: border-box;
            }*/
/*            .child {
             width: 100px;
             height: 0px;
             /*padding-bottom: 50px;*/
             border: 1px solid #000;
             display: inline;
             background: green;
             color: white;
             line-height: 20px;
            }*/
        </style>
    </head>
    <body>
        <div style="font-size: 14px;line-height: 3">
            <div style="font-size: 2em">
                hello
                <span style="font-size: 3em;line-height: 3em">
                    world
                </span>
            </div>
        </div>
    </body>
</html>